Updated: July 24, 2019
Lean-to greenhouses are perhaps one of the most under-sung members of the greenhouse continuum. These small structures are a neat way to extend your growing season without going to a great deal of expense—they’re perfect for gardeners who want to stay close to their hobby plants or indoor food garden. These greenhouses can be covered in plastic or glass and attached to any type of structure to meet your particular needs.
Almost like gardening in the house
When I was growing up I saw a movie where a gardener moved into an apartment with an amazing attached conservatory. I thought it was the most beautiful thing I had ever seen in my life and I still feel that way to this day. Unfortunately, outside of Hollywood, an attached conservatory can set you back tens of thousands of dollars, but you can get a very similar effect with a lean-to greenhouse if you plan it carefully.
Lean-to kits are sometimes available, but because most lean-to greenhouses must be precisely fit to the structures where they’re attached, they tend to be custom built on site. Fortunately, a small structure like this isn’t costly to construct, nor does it take a master carpenter to design. If you place yours on the sunniest side of your home and take advantage of an existing door, you can have easy access from inside without ever having to go out in the rain, snow or wind.
If you grow food year-round, a lean-to greenhouse attached to the kitchen is an ideal way to keep fresh veggies on the table. Although these structures are limited in size, with about 12 feet being the realistic maximum width possible, you can still grow a great deal of lettuce, cucumbers and tomatoes in the space. Some gardeners save their lean-tos for special hobby plants or use them for herb gardens—the smell coming out of an herb-filled lean-to cannot be matched.
More power to you
The greatest advantage to lean-to greenhouses are their ready access to electricity and water when they’re well-placed. It’s really important to have running water and electricity available in your greenhouse—it saves a ton of trouble and mess. When you attach a greenhouse to your home, you can tap into the existing electrical system and plumbing to add these vital utilities to your greenhouse for a fraction of the cost of running buried lines to a free-standing greenhouse.
Power’s great, but so is free heat—when you attach a lean-to to your home, some of the heat that leaks out of the main structure ends up in your greenhouse. It might not be enough to keep the temperature up, depending on where you live, but at the very least, the free heat reduces your energy use.
Despite all that’s great about lean-to greenhouses, there are a few drawbacks to these structures, including:
Ventilation problems – Because of the limited exterior surfaces of a lean-to, you can’t install as many vents, which can lead to problems ventilating your building. This is a bigger problem where summers are very hot and lean-tos are built in areas protected from the wind, such as between two neighboring houses. Ventilation problems can usually be overcome with powered fans placed strategically and additional roof vents.
Light limitation – In order to place your lean-to greenhouse near a kitchen or over an existing porch, you may have to put it in a spot with limited natural light. Even if you can place your lean-to in the best sun available, it will still be shaded by the house for at least part of the day. You’ll need supplemental lighting for most lean-to greenhouses.
Excess moisture – When plants transpire, they push excess water out of openings in their leaves. In turn, this raises the humidity in the greenhouse. In a freestanding greenhouse that’s not much of a problem, but a lean-to is often attached to a wooden structure that may be damaged by the excess moisture. Adding a moisture barrier to the shared wall sometimes solves this problem.
Tracking in dirt – Most gardeners wouldn’t notice if they tracked in a little dirt from the garden, but others are much more picky about mud on the kitchen floor. When you attach a lean-to to your home, you’re inviting dirt and water to be tracked into your living space on a regular basis. Even the cleanest of greenhouses is full of soil, so consider how your lean-to greenhouse will affect your cleaning habits before you take one on.